This invention relates to an apparatus for testing an oil well, and more particularly relates to a full opening closure valve which operates responsive to annulus pressure and includes a reverse circulation valve.
Various tester valves and sampler valves for testing oil wells have been developed over the recent years which are responsive to changes in annulus pressure for opening and closing the valves. Reverse circulation valves responsive either to the operation of an annulus pressure responsive tester valve or responsive themselves to annulus pressure changes have also been developed. For instance, U.S. Pat. No. 3,850,250 issued Nov. 26, 1974 and U.S. Pat. No. 3,930,540 issued Jan. 6, 1975, both to Holden et al and assigned to the assignee of the present invention, disclose a circulation valve which opens after a predetermined number of annulus pressure changes have been applied to the well annulus.
U.S. Pat. No. 3,823,773 issued July 16, 1974 to Nutter discloses a circulation valve which is an integral part of a sampler mechanism wherein the sampler mechanism opens and closes responsive to pressure changes in the well annulus. The circulation valve disclosed therein moves from a closed position to an open position after a predetermined number of operations of the sampler valve. Also pertinent to the present invention is U.S. Pat. No. 3,970,147 issued July 20, 1976 to Jessup et al. and assigned to the assignee of the present invention. That patent discloses a circulation valve which moves to a locked open position repsonsive to an increase in annulus pressure above a given value. One embodiment shows a circulation valve which is an integral part of a sliding sleeve type normally open tester valve, arranged such that the tester valve closes prior to the opening of the circulation valve.
The dual CIP reverse circulating valve offered by Halliburton Services of Duncan, Oklahoma is a reverse circulating valve in which spring loaded fingers hold a sliding sleeve mandrel in a position covering reverse circulating ports in a housing of the valve. The sleeve mandrel is spring loaded toward the open position. The dual CIP reverse circulating valve is operated by drill pipe rotation wherein rotation advances an operating mandrel which also opens and closes a tester valve mechanism. After a predetermined number of rotations the tester valve is closed and additional rotation activates a releasing mechanism which releases the fingers holding the sliding sleeve valve mandrel. The sliding sleeve mandrel is then moved to the open position by the mentioned spring, thereby uncovering the circulating ports to allow reverse circulation.
U.S. Pat. No. 3,856,085 issued Dec. 24, 1974 to Holden et al and assigned to the assignee of the present invention discloses an annulus pressure operated well testing apparatus which includes a full opening ball valve for providing a fully opened passageway through the testing string to the formation to be tested.
The apparatus of the present invention is a normally open closure valve which, when in the open position, provides a fully open flow passage therethrough, and which closes after a predetermined pressure increase has been applied to the fluid in the well annulus. This closure valve may be positioned immediately above a tester valve to ensure that at the end of a program of formation testing the valve string is closed, thus isolating the formation to be tested, before the packer is unseated. The closure valve in the preferred embodiment is a ball valve designed such that the valve is only operated one time during the testing program. This design eliminates wear on the components of the valve to minimize the possibility of the valve failing to fully close when desired. The closure valve includes a reverse circulating valve which is moved to the open position after the closure valve has been closed. The closure valve and the reverse circulating valve are operated by an operating mandrel which disconnects from the operating mechanism of a closure valve after the closure valve is moved to the closed position. The operating mandrel continues to move under the influence of annulus pressure to activate a mechanism for opening the reverse circulating valve.
In the preferred embodiment the closure valve includes two full opening ball valves which operate simultaneously. This arrangement provides that a sample of formation fluid may be trapped between the two full opening valves when they are closed. This arrangement ensures that a representative sample of formation fluid flowing in the testing string during the formation testing program is entrapped by two valves have not been closed heretofore during the testing program.
The activating mechanism for closing the ball valves simultaneously is identical to that disclosed in a U.S. patent application filed on the same date as the present application by Robert Jessup and assigned to the assignee of the present application, and claimed therein as the invention of Robert Jessup.
The invention of the present application results in a closure valve which ensures that the testing string is closed before the packer in the testing string is unseated at the end of a testing program. The closing of the closure valve also initiates the opening of a reverse circulating valve which is not opened until after the closure valve has closed to ensure that pressure transients are not recorded in the well testing recording devices. The closure valve of the present invention also includes a sample chamber between two ball valves which entraps a sample of formation fluid when the closure valve moves to the closed condition. When in the open condition during the testing program the two ball valves provide a fully opened passageway through the closure valve through which various well tools may pass. The fully opened fluid passageway through the closure valve is also highly desirable when testing wells with high flow rate to achieve maximum accuracy in the testing program.